Coin Streak
Classic Jane Street interview game — whose pattern appears first in the coin sequence?
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You
Round 1 of 10
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Computer
Choose Your Pattern
Pick a 2-coin pattern. The computer will pick adversarially using Conway's algorithm.
Key Interview Insight
HH vs HT: HT always wins with probability 3/4. Reason: the sequence must contain a T before HH can occur (since HH needs the run to not be broken). Once we see H, the next flip determines HT vs needing a retry for HH.
Conway's algorithm works because patterns with overlap (like HH) are harder to “chain” — a failed attempt can partially restart the opponent's pattern.